The present invention relates to an eccentric grinder provided with a device for changing a grinding motion so as to adjust the grinder to a coarse grinding and a fine grinding as well.
Eccentric grinders of the foregoing type normally include a device for changing a grinding motion by selecting between a pure eccentric drive of the grinding disc and the drive for the forcible rolling motion of the toothed crowns provided on the housing of the grinder and the grinding disc relative to each other. Such eccentric grinders are available on the market and one of them has been described, for example in "Fachberichte fur Metallbearbeitung", Apr. 3, 1983, title "Rotex, die neue Dimension of Schleifens". Despite certain advantages of the conventional eccentric grinders an optimal adjustment of such grinders to requirements of practice has not been possible. The gap between the pure coarse grinding and the fine grinding is too large. In order to overcome this problem it has been proposed to provide a further drive stage with gears or friction wheels of various diameters which however has been conceivable only with considerable enlargement of the elements which constituted the drive. On the other hand, the switching from one type of the drive to the other type of the drive has involved relatively large expenses on adjustment means. The adjustment means for the drive must be robust and should remain troubleless. When the toothed crowns are employed the teeth of the crows can be damaged during the switching from one drive to another drive.
An eccentric grinder with a device for changing a grinding motion is disclosed in the previously filed U.S. pending application of the same assignee No. 06-921776.